This invention relates generally to dilation devices for the urethra and to the treatment of hypertrophy of the prostate gland. More specifically it relates to novel devices for dilating obstructed portions of the urethra, and to concomitant methods for dilating an obstructed portion of the urethra and for treating benign prostate hyperplasia (BPH).
Benign prostate hyperplasia is a condition which affects well over 50% of the male population over 50 years of age. The treatment of BPH is a matter of great medical and commercial importance. On a worldwide basis, upwards of four billion dollars are spent annually in the treatment of this condition.
There are many devices, techniques and methods which are presently being employed for treating BPH. Surgical treatment of hypertrophy of the prostate has been a routine procedure for many years. One method of such surgical treatment is open prostatectomy wherein the gland is totally or partially removed. Another method of surgical treatment is transurethral resection of the prostate (TURP). However while surgical treatment can be effective it remains an extremely invasive procedure which is debilitating, painful and often traumatic to the patient. Various complications including impotence, incontinence, bleeding, infection and other undesirable problems attendant with such surgery can result. The need for less invasive procedures is therefore of considerable importance.
Among the less invasive procedures now being employed is that of using catheters which are placed in the external opening of the urethra and into at least the obstructed portions of the urethra which allow the passage of urine from the bladder by way of the catheter lumen. These urinary catheters typically employ a positioning or retention balloon at the distal tip which, at the bladder neck, when inflated, prevents the expulsion of the catheter from the body. Illustrative of such positioning balloon catheters are those known in the art as Foley catheters.
It has also been proposed to utilize inflation balloons in addition to positioning balloons for the purpose of dilating obstructed portions of the urethra. Illustrative of such type balloons are those described in U.S. Pat. No. 4,932,958 to Reddy.
It has also been proposed to utilize heat in combination with such catheters for treating the enlarged portion of the prostate, such heat being provided by a variety of means including the use of microwave or laser energy.
Again, while these methods and devices are useful, the search for even less invasive devices and procedures continues. The need for devices and procedures which will result in less pain and discomfort to the patient is of substantial interest, as is the desirability of providing means and devices which will provide for longer term patency of a dilated urethra, i.e. to effect a longer lasting result on relieving the obstruction in the urethra caused by the hypertrophied prostate gland. The latter, due to its resilient fibrous structure and large bulk tends to rebound after treatment of the obstructed urethra is completed, resulting in renewed obstruction.
It would be very desirable, therefore, to provide devices and methods for treating BPH which would be much less invasive and painful, and which would result in dilated urethras of longer patency.
Illustrative of a somewhat less invasive approach is found in the U.S. Pat. No. 4,762,128 to Rosenbluth. This patent discloses an expansion catheter having a rapidly expandable tubular stent associated therewith, which is adapted for transurethral insertion via the external opening of the urethra and for placement within an obstructed region of the urethral lumen caused by a hypertrophied prostate gland. Removal of the expansion catheter leaving in place an expanded tubular stent may result in long term patency of the urethral lumen. Though the stent is also adapted to be removable from the urethra, the intent of the device is to establish a long-term implant.
In U.S. Pat. No. 4,480,642 to Stoy et al, there is disclosed means for the slow dilation of the cervix utilizing a designated dehydrated hydrogel which upon swelling dilates the cervical channel.
In U.S. Pat. No. 4,467,806 to Bhiwandiwala et al, there is disclosed an osmotic cervical dilator using a sponge-like synthetic plastic body in which all the residual spaces are filled with a salt composition and the body is shaped for insertion and retention in the cervix, said dilator being slowly expandable.
In U.S. Pat. No. 3,867,329 to Halpern et al, there is disclosed a chemically actuated dilation device for insertion into the cervix or other body opening. The device to be inserted comprises a closed rod-like member composed of a hydrogel capable of expanding by the absorption of body or other fluids.
In U.S. Pat. No. 5,163,952 to Froix there is disclosed an expandable stent for use in a lumen defined by a wall of a vessel, which illustratively is defined as an arterial vessel in the heart. The polymeric stent has a built-in elastic predetermined diameter and a memory of a diameter greater than the predetermined diameter which is assumed upon activation of a thermal activation point by the adsorption of heat by the plastic, adsorption of liquid by the plastic, or a change in the pH of the liquid surrounding the plastic.
In U.S. Pat. No. 4,237,893 to Michaels there is disclosed a cervical dilator, sized, shaped and adapted to occlude the length of the cervical canal. The dilator comprises a base and a laminate formed of a swellable polymer.
In U.S. Pat. No. 4,434,797 to Silander there is disclosed a catheter for a body duct, vessel or cavity, which comprises an outer casing which entirely or partially covers the catheter and consists of a hydrophilic substance capable of absorbing liquid.
In U.S. Pat. No. 5,234,456 to Silvestrini there is disclosed a hydrophilic stent for a body lumen comprising a wall structure, at least a portion of which is hollow, which has a hydrophilic material disposed therein which can swell upon the introduction of a liquid.